Electromagnetic shuttle for sewing machines



Sept. 2, 1952 HAGQUlST ELECTROMAGNETIC SHUTTLE FOR SEWING MACHINES Filed Sept. 13, 1948 //////1// l l \\N Patented Sept. 2,1952

ELECTROMAGNETIC SHUTTLE FOR SEWING MACHINES Arne Hagquist, Oslo, Norway Application September 13, 1948, Serial No. 49,056 In Norway November 1, 1947 7 Claims.

The present invention relates to an improved sewing machine.

In one form of sewing machine at present in common use, a loop formed in the needle thread is caught by a rotary hook and carried around a bobbin-case containing the under-thread. The case is thus enclosed by the over-thread and the stitch is formed when the needle-thread is tightened.

Because the needle-thread has to be carried under the bobbin-case the latter must be quite light to avoid breaking the needle-thread. For this reason bobbins of small capacity have to be used, necessitating frequent rewindings.

It is one object of the present invention to provide a machine in which an ordinary reel of relatively large capacity can be used in place of the hitherto-used bobbins of small capacity.

In accordance with the invention there is provided a sewing machine having a rotary hook for passing a loop of the needle-thread around a bobbin-case holding the under-thread, and electromagnetic means for floating the case in midair whilst the loop is passed aroundit.

According to another aspect of the invention there is provided a sewing machine comprising a magnetizable bobbin-case holding the underthread, a rotary hook for passing a loop of the needle-thread around the bobbin-case, means for producing an electromagnetic field around the bobbin-case and means for periodically reversing the direction of the field in synchronism with the rotation of the hook in such a way that the loop is passed around the case whilst the latter is floating in mid-air in the field.

Since the bobbin-case floats in an electromagnetic field ordinary reels can be placed in it without risk of the thread beingbrcken.

The bobbin-case is preferably open at one end to allow the reel to be inserted on to a spindle with the inside of the case. The spindle is formed of two lengths of magnetic material separated by a length of non-magnetic material.

On either side of thecase are a pair of magnets which are coaxial one with the other and with a driving shaft for. the rotary hook. Means are provided for energizing the magnets alternately to cause the case to be reciprocated between them, thus leaving space for the needlethread to be looped around the case. The mag nets are preferably electromagnets the windings of which are energised alternately with the aid of a commutator on the driving shaft.

The ends of the magnets carry cup-shaped tips which correspond in shape with that of the bobbin-case.

The driving shaft is hollow and encloses a stationary tube holding one of the magnets and'its cup-shaped tip.

The machine is provided with an ordinary-ro tary hook, fast on the driving shaft, enclosing one of the electromagnets and cooperating with the bobbin-case in forming the stitch in the usual way.

A preferred form of the invention will now be described with reference to the accompanying diagrammatic drawings in which:

Figure 1 is a side elevation, partly in section, of a sewing machine,

Figure 2 is a section, on a larger scale, of a portion of the machine shown in Figure 1, and

Figure 3 is a perspective view ofthe apparatus shown in Figure 2, but dismantled.

A driving shaft I under the body of the machine is hollow and runs in a bearing 2, being driven, either by hand or with electric power, with the aid of a belt 3. Fast on the shaft 1 so as to rotate with it is a hook-carrier 4 carrying a hook 5.

The hollow shaft I encloses partially a stationary tube 6 carrying at its end an electromagnet l and winding 8. Coaxial with the electromagnet l, and spaced from it, is a second and similar electromagnet 9 and its winding l0. i

The electromagnets carry cup-shaped tips II and I2 respectively between which is located a bobbin-case l3 of shape corresponding substantially with that of the tips I l and l 2.

Thus the case I3 is in the form of a pair of conical frustums having their bases joined; one narrower end being and the other end being closed and carrying internally an iron core or spindle l4. v

The peg is formed of two lengths of magnetizable material separated by a length [8 of nonmagnetizable material and serves both to hold a reel and as an armature'common to the two electrogmagnets I and 9.

The windings of the electromagnets are-connected to a commutator l5 which is mounted on the main shaft of the machine and is so constructed that each winding is alternately energised and de-energised, one being energised when the other is de-energised in synchronism with the rotation of the hook, so that the bobbin-case is reciprocated axiall between the tips H of the electromagnets in such a way as to leave the case floating in mid-air between the magnets each time the hook brings the needle-thread loop around the case.

The under-thread emerges from the bobbincase l3 through a slot 11, under the control of ing efiective when energized to produce a mag.

netic field in the space therebetween causingsaid case to be floated therein, and said field constituting the sole support for said case during the sewing operation, and means for energizing said electromagnets alternately in timed relation with the rotation of said hook to impart an axial reciprocatory motion to said bobbin case in the space between said electromagnets.

2. An electromagnetic shuttle device for sewing .machines comprising a pair of electromagnets having pole tips arranged in confronting relation, a magnetizable bobbin case for holding the underthread disposed between said pole'tips, said electromagnets being effective when energized to produce a magnetic field in the space between the pole tips causing said case to be floated therein, and said field constituting the sole support for said case during the sewing operation, a rotary hook for passing a loop of the needlethread around-said bobbin case, and means energizing said electromagnets alternately in timed relation with the rotation of said hook to impart a reciprocatory motion to said bobbin case in the space between said pole tips.

3. An electromagnetic shuttle device for sewing machines comprising a pair of electromagnets having pole tips arranged in confronting relation, a magnetizable bobbin case for holding the underthread disposed between said pole tips, said electromagnets being effective when energized to produce a magnetic field in the space between the pole tips causing said case to be floated therein, and said field constituting the sole support for said case during the sewing operation,

a rotary hook for passing a loop of the needlethread around said bobbin case, said hook being provided on a rotatable carrier, drive shaft means for rotating said hook carrier, and means including commutator means on said drive shaft means for energizing said electromagnets alternately in timed relation with the rotation of said hook carrier to impart a reciprocatory motion to said bobbin case in the space between said pole tips.

4. An electromagnetic shuttle device for sewing machines comprising a pair of electromagnets having cup-shaped pole tips arranged in confronting relation, a magnetizable bobbin case for holding the under-thread disposed between said pole tips, said electromagnets being efiective when energized to produce a magnetic field in the space between-the pole tips causing said case to be floated therein, and said field constituting the sole support for said case during the sewing operation, the exterior of said bobbin case being of generally the same shape as the interior of said pole tips and partly nested in the latter, a rotary hook for passing a loop of the needle thread around said bobbin case, and means energizing said electromagnets alternately in timed relation with the rotation of said hook to impart a reciprocatory motion to said bobbin case in the space betweensaid pole tips.

5. An electromagnetic shuttle device for sewing machine as defined in claim 4 wherein said bobbin case includes an inner bobbin spindle, said bobbin case being open at the free end of said spindle to receive the bobbin, and said spindle separated by non-magnetizable material constituting an armature common to said electromagnets.

6. An' electromagnetic shuttle device for sewing machines comprising a pair of electromagnets disposed in axial alignment and including cupshaped pole tips arranged in confronting relation, a magnetizable bobbin case for holding the underthread disposed between said pole tips having Walls generally corresponding in shape to said pole tips and partially nested within the latter, said electromagnets being effective when energized to produce a magnetic field in the space between the pole tips causing said case to be floated therein, and said field constituting the sole support for said case during the sewing operation, a bobbin spindle within said bobbincase extending longitudinally of the axis of said electromagnets, said bobbin case being open at a free end of said spindle to receive the bobbin and including end sections of magnetizable material separated. by non-magnetizable material constituting an armature common to said electromagnets, a rod extending axially of and supporting one of said electromagnets, a hollow shaft surrounding said support rod, a hook for passing a loop of the needle-thread around said bobbin case, a carrier for said hook surrounding said rod supported electromagnet and united with-said hollow shaft, means for rotating said hollow shaft, and means including a commutator device for energizing said electromagnets alternately in timed relation with rotation of said hook to impart a reciprocatory motion to said bobbin case in the space between said pole tips along the axis of said electromagnets.

7. An electromagnetic shuttle device for sewing machines as defined in claim 6 wherein said rod is hollow and the connecting wires to the electromagnet supported thereby extend therethrough.

ARNE HAGQUIST.

' REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 983,902 Hohmann Feb. 14, 1911 FOREIGN PATENTS Number Country Date 45,795 Netherlands Apr. 16, I939 

